1. Field of Invention
The present invention relates, in general, to a method of determining a failure of an active air flap (AAF) in which openable flaps are installed at the back of a radiator grill and bumper grill so as to control an inflow of air for cooling a vehicle engine.
2. Description of Related Art
Generally, an active air flap system is a system in which openable flaps are installed at the back of a radiator grill and bumper grill to control an inflow of air for cooling a vehicle engine. This system is operated such that it receives information of a vehicle (a temperature of cooling water, ON/OFF switch of an air conditioner, pressure of cooling medium) from an electrical control unit (ECU) via controller area network (CAN) communication so as to allow and block an inflow of external air according to the state of the vehicle, effecting an improvement of fuel efficiency through a reduction in air resistance, an improvement of heating performance through shortening the time for which a vehicle engine operates at a low temperature, a reduction of exhaust gas through rapid warming-up of an engine, and so forth.
However, such a newly employed system develops frequent problems, even becoming the cause of laying field claims. In other words, although an active air flap becomes defective on account of broken wires or a short-circuit, it may also temporarily malfunction because of simple freezing. In this case, the freezing may be naturally eliminated by the heat of the engine. However, if such a case is also determined that leads to a failure occurring in the system, a driver may feel uneasy about driving a vehicle, and reliability of the system is reduced.
Recently, some manufacturers have thus been willing to reduce the range of applications of the active air flap because of such problems.
Thus, as no definite factor now stands to distinguish between the freezing of the flap in wintertime and a failure of the air flap system, there is a problem of adaptation of the active air flap.
According to the conventional control logic to determine a failure of the active air flap, the freezing diagnosis is carried out simply using TAM temperature of ECU of the engine (the temperature of a temperature sensor installed in the side of the engine) to determine a condition of freezing. Here, if the flap is constrained below 15° C. of the TAM temperature, it is determined to be frozen.
However, this method has a problem in that the error range of temperature is excessive (±10° C.), effective condition on the TAM temperature exists, and the freezing is determined only using the TAM temperature, making it very difficult to precisely distinguish between the freezing and the failure.
Thus, there is a need to optimize the system to determine either the freezing or failure of the active air flap such that an engine-trouble lamp is not frequently turned on through frequent, unnecessary alert to a failure of an engine.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.